Our understanding of stellar evolution is built upon a synergy between observations and theory. Careful and thorough observations of open clusters provide a laboratory, of sorts, for testing theories and revealing where our current understanding of stellar evolution falls short. Complete membership studies of open clusters reveal that 25% of the evolved stars do not agree with simple stellar evolutionary models, but instead follow alternative pathways in stellar evolution. In order to draw a comprehensive picture of stellar evolution we must include these canonically "strange" stars in our definition of standard stellar populations. The majority of these alternative pathway stellar products are blue straggler stars, whose dominant formation mechanism has been an outstanding question for almost six decades. In this talk I will review the current state of blue straggler observations and formation theories, focusing on recent developments in studies of blue straggler stars in cluster environments. I will then present my own work on determining the mass transfer formation frequency of blue straggler stars in open cluster NGC 188 using Hubble ultraviolet photometry, and illustrate how these blue stragglers will help to redefine detailed binary mass transfer models.